A known form of seal comprises a polymeric resilient foam core and an enveloping cover in the form of a thin film of polymeric material. Such seals have been made by shaping the bottom of an elongated strip of the film about a longitudinal dimension of the strip, laying in material that will foam and overlapping the edges of the film to form a hollow tube-like structure and then foaming the material to form the resilient core, as disclosed in U.S. Pat. Nos. 3,700,368, 3,781,390 and 3,941,543. As the film, being uniformly thin and flexible, does not provide any rigidity to the seal, it is conventional to incorporate an elongated relatively rigid element as an aid in attaching the seal to another structure. On occasion the overlapped edges of the film allow some of the foam to bleed through or escape during the foaming step, resulting in an unsightly or defective product.
One object of the present invention is to provide a seal comprising a resilient elongated foam core enveloped around its circumference by a cover of polymeric material, the cover having a flexible hollow portion filled with at least part of the core and having at least one relatively rigid flange-like, portion protruding laterially and extending the length of the seal for attaching the seal to another structure. Preferably the cover is formed by extruding the flexible and rigid portions simultaneously in such a way that the portions become bonded to each other edge-to-edge as they are extruded, thereby forming a single integral member. In particular, the cover can be formed by extruding three portions, one extrusion forming a flexible longitudinal central portion of the integral member and the other two extrusions being relatively rigid and being bonded to opposite edges of the central portion. The member is then shaped around a longitudinal dimension to form a hollow structure into which foamable material is placed.
Another object of the present invention is to provide a seal comprising a resilient elongated foam core enveloped around its circumference by a cover, the cover being formed as a separate element having interlocking edge portions extending longitudinally of the seal. This configuration is particularly advantageous when the seal is made by shaping the preformed cover into a hollow tube-like structure, as referred to above, because by interlocking the edge portions of the cover the tendency of the polymeric foam to bleed or escape is eliminated. Preferably the edge portions are rigid relative to the central portion and together form a reinforcing or stiffening member in addition to performing a locking function.